Venous electrical stimulation apparatus and methods and uses thereof

ABSTRACT

An electrical venous stimulation apparatus comprising an electrical signal generator, the signal generator configured to generate a specified electrical output signal. The apparatus also includes a plurality of electrodes in electrical communication with the signal generator and configured to be placed in electrical communication with a subject. The electrical output signal sent to the subject includes an output voltage, electrical current, and waveform that changes with time in a preprogrammed repeating cycle. The output voltage, electrical current, and waveform are configured to elicit a physiological response that stimulates a plurality of peripheral nerves in the subject, activates a venous muscle pump mechanism in one or more limbs of the subject, and non-invasively alter the physiology of target vein(s), wherein the target vein(s) is caused to distend from under the surface of the subject&#39;s skin.

This application is a continuation of U.S. patent application Ser. No.14/917,745, filed on Mar. 9, 2016, which is a National Stage entry andclaims priority to International Application No. PCT/US2014/055551,filed on Sep. 15, 2014, which claims priority to U.S. Provisional PatentApplication No. 61/878,869, filed on Sep. 17, 2013, the contents ofwhich are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

This disclosure relates to medical devices for providing improved venousaccess to aid in the drawing of blood from, administering fluids ordrugs via, or insertion of a peripheral intravenous cannula into, theveins of a patient.

BACKGROUND

The single standard practice for gaining peripheral venous access in amedical patient has not changed significantly in over 80 years.Typically, the standard practice involves the use of a tourniquetapplied to an upper portion of a patient's arm. The application of atourniquet stops the flow of blood to the heart and allows whateverpressure is available from the arteries and capillaries to fill anddistend the veins. A medical practitioner, such as a doctor, physician'sassistant, paramedic, or nurse, may then access the distended vein witha needle to draw blood, or insert a peripheral venous catheter or othersuch cannula into the distended vein to administer drugs or otherfluids. This is a painful, sometimes dangerous, time consuming, andinaccurate method.

In a majority of patients, this approach is sufficient for either thedrawing of blood for hematology analysis, or for the placement of anintravenous cannula to administer fluids, including but not limited tovolume expanders (e.g., colloids (e.g., blood, dextran, hydroxyethylstarch, stroma-free hemoglobin), crystalloids (e.g., normal saline,Ringer's Lactate, glucose/dextrose, Hartmann's Solution), blood-basedproducts (e.g., red blood cells, plasma, platelets), blood substitutes(e.g., oxygen-carrying substitutes), buffer solutions (e.g., intravenoussodium bicarbonate, Ringer's Lactate), nutritional formula (e.g.,peripheral parenternal nutrition), or drugs including but not limited toantibiotics, analgesics or chemotherapy into the blood stream of apatient. However in most patients, geriatric patients or cancertreatment patients for example, gaining venous access can be difficultand problematic for any number of reasons, which may lead to medicalpractitioners requiring multiple repeated attempts to successfully gainintravenous access to the patient's vein(s). Repeated attempts, to gainvenous access in a patient may result in a variety of adverse issuesincluding hematomas, fluid infiltration into the surrounding tissue(which, with chemotherapy agents, can cause severe local reactions),pain, shock, discomfort, vasoconstriction, and in emergency situations,may require the practitioner to switch to either a central venous accessapproach or a “cut-down” (opening the tissue) to gain access to a vein.

There are many types of patients in whom these problems can result.Elderly or geriatric patients frequently have frail veins or areperipherally shut down due to dehydration. Pediatric and neonatal(newborn) patients are especially difficult to gain venous access to,due to small veins and the significant immaturity of their bodies.Patients who have lost blood volume through trauma, shock, ordehydration (such as ER and paramedic patients, patients injured in roadtraffic accidents or military combat, crush victims, famine victims,etc.) are likely to be peripherally shut down, making it difficult tolocate and raise a vein, but are often the patients in whom medicalpractitioners most rapidly need to gain venous access. Obese patientsare yet another patient group in which medical practitioners encounterdifficulties in locating or raising a vein for venous access. Cancertreatment patients also present difficulties for medical practitionersto gain venous access due to, among other things, phlebitis.

Other methodologies and devices have been employed to attempt to locatetarget veins for venipuncture or determine when a proper and successfulvenipuncture has been achieved. However, such devices and methodologiesare either passive and non-invasive devices and techniques, or they areinvasive mechanical devices and techniques that actually first requirethe puncture of the target vein in order to determine the position ofthe needle within the vein (which does not otherwise aid in locating thetarget vein or increasing the ease of inserting the needle into thetarget vein). One example of a passive technique and device is the useof a strong source of visible or ultraviolet light placed against theskin of the patient in an attempt to read the reflectivity of theunderlying iron in the patient's red blood cells in the target vein,through the patient's skin. While this passive technique may help tolocate a target vein, it does not increase the ease of achievingsuccessful venipuncture. Additionally, the vein will often roll awayfrom the needle when the medical practitioner tries to inset it. Thedrawback to using active mechanical devices that need to puncture thelumen to determine the position therein is that, if the machineperforming the venipuncture goes too far and pushes the needlecompletely through the opposite side of the target vein, the result is adouble penetration of the vein requiring the tip of the needle to bewithdrawn back into the lumen of the vein. Accordingly such mechanicaltechniques are flawed in that they permit the possibility of a doublepenetration which may result in blood leaking from the second veinpuncture causing a hematoma in the patient.

Accordingly, there is a need for a more rapid, reliable, less painful,more efficient, safer, and repeatable method of distending a patient'sveins in the hands, arms, feet, or legs to allow easier venous access bymedical practitioners. In addition, there is a need for a medicalapparatus that can cause a more rapid, reliable, and repeatabledistension or expansion of veins in a patient's hands, arms, feet orlegs across a broader patient spectrum including geriatric, pediatric,neonatal, and trauma patients, to assist medical practitioners ingaining venous access.

SUMMARY

In general terms, this disclosure is directed to electrical venousstimulation. In one possible configuration and by non-limiting example,the electrical venous stimulation is used to provide improved access toa vein. Various aspects are described in this disclosure, which include,but are not limited to, the following aspects.

One aspect is an electrical venous stimulation apparatus, for causingtarget veins in a subject to distend from under the surface of thesubject's skin, comprising: a power supply, a signal generator poweredby the power supply, the signal generator configured to generate aspecified electrical output signal, and a plurality of electrodes inelectrical communication with the signal generator and configured to beplaced in electrical communication with the subject, wherein theelectrical output signal includes an output voltage, electrical current,and waveform that changes with time in a preprogrammed repeating cycle,the output voltage, electrical current, and waveform being configured toelicit a physiological response that stimulates a plurality ofperipheral nerves in the subject, activates a venous muscle pumpmechanism in one or more limbs of the subject, and non-invasively alterthe physiology of a target vein, wherein the target vein is caused todistend under the surface of the subject's skin.

Another aspect is a method of stimulating peripheral target veins tocause the veins to distend under the surface of a subject's skin tofacilitate venipuncture, comprising: generating an adjustable electricaloutput signal with an electrical venous stimulation apparatus, thesignal including an adjustable output voltage, an adjustable current,and an adjustable output voltage waveform configured to elicit aphysiological venous response in the subject that causes the target veinin the subject to distend under the surface of the subject's skin, theelectrical stimulation apparatus including, a powered signal generatorconfigured to generate the adjustable electrical signal, and a pluralityof electrodes in electrical communication with the signal generator andconfigured to be placed in electrical communication with the subject;and transmitting the output signal to the subject via the plurality ofelectrodes.

A further aspect is a method of suppressing pain signals at a venousneedle stick site of a subject, comprising: generating an adjustableelectrical output signal with an electrical venous stimulationapparatus, the signal including an adjustable output voltage, anadjustable current, and an adjustable output voltage waveform configuredto elicit a physiological venous response in the subject that causes thetarget vein in the subject to distend under the surface of the subject'sskin, the electrical stimulation apparatus including, a powered signalgenerator configured to generate the adjustable electrical signal, and aplurality of electrodes in electrical communication with the signalgenerator and configured to be placed in electrical communication withthe subject; and transmitting the output signal to the subject via theplurality of electrodes, and thereby stimulating the peripheral nervesand activating the venous pump mechanism in at least one limb of thesubject.

A further aspect is a method of accessing a vein of a person, the methodcomprising: receiving a portion of a limb of the person into acontainer; supplying a liquid electrolytic solution into the container,wherein the liquid electrolytic solution is in contact with the portionof the limb; electrically stimulating the portion of the limb with atleast one signal generated by an electrical signal generator, theelectrical signal provided to the electrolytic solution by at least oneelectrode in contact with the liquid electrolytic solution; causing atleast one vein in the limb of the person to distend in response to theelectrical stimulation; and inserting a tip of a needle into the veinwhile it is distended to access the vein.

Another aspect is a venous electrical stimulation apparatus fortemporarily enlarging and distending the peripheral veins in the limbsof a patient to make it easier for a medical practitioner to gain venousaccess when drawing blood or when inserting an intravenous cannula, suchas a catheter, into the vein. The venous electrical stimulationapparatus is configured to stimulate one or more muscles that form ananatomical part of the vein to cause the circumference of the vein'slumen to enlarge, thus making the target vein press against the skin,and simultaneously creating a vacuum in the target vein that can helpincrease the total volume of blood within the vein, which also helpsmake it easier and safer to perform venipuncture.

Yet another aspect is an apparatus that includes a signal generatorhaving a pair of electrical output terminals, a power supply inelectrical communication with the signal generator, at least a pair ofelectrical leads in electrical communication at a proximal end with theoutput terminals of the signal generator, and at least a pair ofelectrodes in electrical communication with the proximal ends of theleads, and configured to introduce the electrical signal into a patient(or subject). The patient or subject can be a mammal, and morespecifically, a human.

In another aspect the apparatus is configured to non-invasively alterthe physiology of the peripheral veins that are targeted forvenipuncture in the limbs of a patient using an active electricalsignal, rather than using passive means traditionally used or requiringthe use of a tourniquet. In an aspect of the present disclosure, anactive signal imparted to the skip of a patient by the apparatus elicitsa physiological response and a change in condition/behavior of thetarget vein, causing the vein to fill with blood and becomedistended/enlarged and become more rigid, therefore increasing thevisibility of the vein through the skin. In this manner, using such anapparatus and methodology, it becomes easier for medical practitionersto achieve successful and proper venipuncture. No other active devicecurrently exists that non-invasively changes the physiology of thetissue in and around the target veins to aid in locating the target veinand increasing the ease of achieving successful and proper venipuncturewithout the need for multiple attempts.

In yet another aspect, the electrical signal generator includes aplurality of capacitors and resistors, and at least one potentiometerfor adjusting the output voltage. The electrical signal generatorfurther includes programming configured to adjust the output signal,which may include one or more of the output voltage, output current,output voltage waveform, and/or signal frequency that is imparted to thepatient over time, to stimulate the venous pump action in the motormuscles of the patient's limbs resulting in distension of the peripheralveins of a patient. In one embodiment, the electrical signal generatoris configured to change the output voltage and the shape of the outputvoltage waveform. The output voltage determines how many muscle fibersare recruited and fired (i.e. the muscle stimulation portion of thewaveform), as well as how much energy is used to fire the nerve impulsesacross the synaptic junction. The shape of the output voltage waveformdetermines what information is communicated to the brain.

In another aspect, the electrical signal generated is an AC signal ofless than one milliamp and the output voltage from the potentiometer isin the range of 0 to 90 volts.

In another aspect, the electrical signal generator generates a specificpredefined output voltage waveform that is imparted to the skinoverlying the limbs of the patient. One portion of the generatedelectrical waveform is specifically tuned to the frequency, duty cycle,pulse width, and voltage at which the tiny muscles surrounding thetarget veins exhibit a physical response, resulting in muscularexpansion and contraction. This predefined waveform and the resultingresponse in the veins makes them rigid and enlarges their circumference.Another portion of the predefined waveform stimulates the nearby nervesin the skin to override any pain signals in the body resulting front theneedle stick. This nerve stimulation reduces the pain and anxietyusually accompanying a venipuncture. Still another portion of theelectrical signal stimulates the brain to release endorphins to thebody, thereby reducing anxiety in the patient.

In another aspect of the present disclosure is a method of providingmedical practitioners with peripheral venous access in patients whilesuppressing pain signals at a venous needle stick site by stimulatingthe peripheral nerves and activating the venous pump mechanism in thelimbs of a patient using an external electrical stimulation apparatus,thereby causing the peripheral nerves to distend and become more visibleunder the surface of the skin.

In another aspect, for non-emergency patients, one benefit to using someembodiments disclosed herein is the reduction of the time spent bymedical practitioners acquiring venous access and the reduction of thenumber of failed attempts at venous access in patient groups whommedical practitioners historically have had difficulties gaining venousaccess. Furthermore, in emergency situations and for emergency patients,having the ability to gain rapid venous access can increase the speedwith which vital fluids and/or drugs may be administered, therebypotentially saving vital minutes and patient lives.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures are for illustration purposes only and not necessarily drawnto scale. However, the present disclosure may be best understood byreference to the detailed description which follows when taken inconjunction with the accompanying drawings.

FIG. 1 is a top front isometric view of an example embodiment of anelectrical vein stimulation and expansion apparatus of the presentdisclosure.

FIG. 2 is a top isometric view of the electrical vein stimulation andexpansion apparatus of FIG. 1, showing the cover of the electricalsignal generator in an open position to expose the internal circuitryand electrical components of the example electrical signal generator.

FIG. 3 is another top isometric view of the electrical vein stimulationand expansion apparatus of FIG. 1.

FIG. 4 is another top front isometric view of the electrical veinstimulation and expansion apparatus of FIG. 1, showing the apparatusready for use wherein a patient has her fingertips placed in containersof electrolyte solution that are electrically connected to the signalgenerator of the apparatus.

FIG. 5 is a another top front isometric view of the electrical veinstimulation and expansion apparatus of FIG. 1, showing the apparatus inuse and illustrating the distending and protruding of the patient'sveins.

FIG. 6 is an electrical schematic of an embodiment of a signal generatorof the electrical vein stimulation and expansion apparatus of thepresent disclosure.

FIG. 7 is a waveform graph of the output voltage vs. time for one cycleof the output signal, such as generated by the signal generator shown inFIG. 6.

FIG. 8 is a waveform graph illustrating another example waveform.

FIG. 9 is a waveform graph illustrating another example waveform.

DETAILED DESCRIPTION

Various embodiments will be described in detail with reference to thedrawings, wherein like reference numerals represent like parts andassemblies throughout the several views. Reference to variousembodiments does not limit the scope of the claims attached hereto.Additionally, any examples set forth in this specification are notintended to be limiting and merely set forth some of the many possibleembodiments for the appended claims.

While the present disclosure is capable of embodiment in various forms,there is shown in the drawings, and will be hereinafter described, oneor more presently preferred embodiments with the understanding that thepresent disclosure is to be considered as an exemplification of theinvention, and is not intended to limit the invention to the specificembodiments illustrated herein. Headings are provided for convenienceonly and are not to be construed to limit the invention in any way.Embodiments illustrated under any heading may be combined withembodiments illustrated under any other heading.

Referring to FIGS. 1-5, in general, disclosed herein is an electricalstimulation apparatus 1 configured to deliver an electrical signalthrough the arms or other limbs of a patient and cause the veins in thehands and/or arms of the patient to distend or expand and thereby becomemore visible under the surrounding surface of the skin. Such signals canbe delivered directly to one limb; up one limb, up through the limb,across the spine, and/or down through the other limb, for example. Indoing so, the stimulation apparatus makes the peripheral veins in thearms or hands of the patient more visible, thereby providing a medicalpractitioner venous access for the drawing of blood or the insertion ofa peripheral venous cannula. The apparatus is generally placed inelectrical communication with a patient's hands and/or arms (or otherlimbs) by a pair of electrodes or other electrical signal deliverydevice, that connects the device to the patient's arms to deliver apredetermined electrical signal through the electrically connected limbsof the patient.

The veins thus become filled with blood while being subjected to theelectrical stimulation, increasing the internal pressure within theveins. The increased pressure in the veins makes them more rigid,thereby increasing the physical resistance, or force, required to inserta needle or other intravenous cannulas therein. The increased physicalresistance of the target vein permits the medical practitioner to havean improved physical feed for the insertion of the needle into the vein,and to better differentiate instances when the tip of the needle hasbeen correctly inserted into the central lumen of the vein, frominstances in which the needle has pierced through the vein (which cancause serious medical complications).

In general, the electrical stimulation apparatus 1 comprises anelectrical signal generator 10, a power supply 12 in electricalcommunication with the signal generator and configured to supply powerthereto, at least a pair of electrical leads 14 connected at a proximalend to a plurality of electrical output terminals 16 of the electricalsignal generator, and at least a pair of electrodes 18 connected to adistal end of each of the electrical leads 14.

The electrical power supply 12 may be a portable power supply, such asfor example a 9-volt battery, other voltage battery, or rechargeablebattery. Alternatively, the power supply may utilize a standardelectrical power cord that plugs into a typical power outlet in a wall.

An example of the electrical signal generator 10 is shown in FIG. 6.Also shown in FIG. 6 are the power supply 12, electrical lead 14,container 28, and electrolytic solution 30. Some embodiments include twoor more electrical signal generators 10, coupled to one or more leads14, electrodes 18, and containers 28.

The electrical signal generator 10 comprises electronic circuitry 20operable to generate an electrical output signal, such as having one ofthe waveforms illustrated and described with reference to FIGS. 7-9, oranother suitable waveform. In some embodiments the electronic circuitry20 includes electronics such as one or more of resistors, capacitors,transformers, and a microprocessor in electrical communication with eachother. In the example shown in FIG. 6, the electronic circuitry 20 ofthe electrical signal generator 10 includes a power switch 50,oscillator 52, variable control 54, and output circuitry 56. In thisexample the oscillator 52 includes an integrated circuit, such as amicrocontroller 62. The output circuitry 56 includes a first stage 58,such as including operational amplifiers 64 and 66 and capacitor 68, anda second stage 60, including transformer 70. The output of the secondstage 60 forms the output terminal 16, which can be electrically coupledto the lead 14 and electrode 18, to deliver the output signal to thepatient.

The oscillator 52 operates to generate an initial oscillating signal. Inthis example, the oscillator includes a square wave generator. Oneexample of a square wave generator is a microcontroller, such as the8-pin, flash-based 8-bit CMOS microcontroller, part number PIC12F675available from Microchip Technology Inc. of Chandler, Ariz., US. Anotherexample of a square wave generator is a 555 timer. The square wavegenerator produces a squarewave signal, which oscillates between low andhigh voltages, such as between 0 and 5 volts. In this example the squarewave has a frequency in a range from 4 Hz to 12 Hz. As one example thefrequency is 7.83 Hz. Frequencies in this range have been found to bepreferred over faster frequencies because they give the nerves in thepatent time to repolarize after stimulation before the next stimulation.The frequency can be higher for a healthy person whose nerves canrepolarize more quickly, while the frequency typically needs to be lowerfor an unhealthy person whose nerves require more time to repolarize.

In some embodiments the signal generator 10 includes a variable control54, such as one or more potentiometers 22, 24 in electricalcommunication with the electronic circuitry of the signal generator 10.The one or more variable controls 54 allow an operator, such as amedical practitioner, the patient, or another person to provide an inputto adjust the magnitude of the signal generated by the signal generator10, such as to increase or decrease the magnitude of the signal. In thisexample, each potentiometer 22, 24 that is present in the signalgenerator corresponds to a separate output voltage channel (each havingits own signal generator 10) having its own leads 14 and electrodes 18,and whose voltage is adjusted by its own intensity adjustment knobcoupled to the variable control 54 that adjusts/sets the output voltageof that channel that is sent from the signal generator 10 to the patientvia the leads 14 and electrodes 18. The ability to adjust the outputvoltage experienced by the patient allows a patient to have the voltageadjusted down to a comfortable level, which therefore contributes tolowering the patient's anxiety over use of the device, which thusreduces the chance of any anxiety or stress induced vasoconstrictionthat can reduce the amount of blood within the targeted veins.

In one embodiment, the signal generator 10 includes two variablecontrols (e.g., potentiometers 22, 24), and therefore may have twoseparate output voltage channels each having its own signal generator10, with each intensity knob and variable control 54 separatelyadjusting the output voltage to be sent to the patient along two sets ofelectrodes, corresponding to each of the two output voltage channels. Afirst of the two potentiometers 22 and its respective output voltagechannel impart an output voltage to the patient that is configured tocause the target vain to become swollen or distended. A second of thetwo potentiometers 24 and its respective output voltage channel impartan output voltage to the patient that is configured to stop the pain atthe needle stick site by interrupting nerve signals associated withpain. In the present embodiment, the two output voltage channels areidentical, but in alternate embodiments, each potentiometer may beconfigured to adjust the output voltage in differing ranges. Having twoseparate channels, each with the ability to adjust the output voltage,allows the stimulation apparatus 1 to be configured to adapt to targetveins in the foot, neck, elbow, or other such target vein sites.

In this example the electronic circuitry 20 of the signal generator 10further includes output circuitry 56. The output circuitry operates toconvert the square wave signal generated by the oscillator 52 into adesired output signal, such as having a waveform shown in one of FIGS.7-9.

The first stage 58 of the output circuitry includes electronicsincluding operational amplifiers 64 and 66, and a capacitor 68. Thefirst stage 58 is coupled to the variable control 54 to receive theinput from a user to adjust the magnitude of the signal generated by thesignal generator 10. In this example, the variable control 54 is apotentiometer that provides a variable resistance. The variable control54 is electrically coupled to an input of the operational amplifier 64.The voltage of the signal provided by the variable control 54 changesthe variable control is adjusted. The operational amplifier 64 isconfigured as a unity gain buffer amplifier in this example. In someembodiments the variable control operates to adjust the magnitude of anoutput voltage so that magnitude is adjustable from 0 volts to 40 volts.In some embodiments the maximum output voltage is within +/−10% of 40volts. Other embodiments have other ranges of output voltages. In someembodiments the current delivered depends on the patient's naturalelectrical resistance, the surface area stimulated, and other factorssuch as the conductivity of the connecting medium (e.g., water, vs gel),self adhesive electrodes, amount of oil on skin, capacitance of thepatient, and other technical/anatomical factors such as dehydration andthe stress level of the patient.

The oscillator 52 generates a square wave output (e.g., pin 7) that isthen supplied to the capacitor 68. The capacitor 68 converts the squarewave signal to a series of pulses having a leading edge with a sharpvoltage transition, followed by a trailing edge in which the voltagetapers off. The signal is then provided to the second stage 60 where itis further filtered and amplified such as using the amplifier includingoperational amplifier 66 arranged in a non-inverting configuration.

The amplified signal is then provided to the second stage 60, includingthe transformer 70, which operates to amplify and rectify the signal.

In some embodiments the transformer 70 has an unequal ratio of windings.As one example, the transformer is a 10:1 transformer, which is arrangedin a step-up configuration to increase the voltage at the output. Inother possible embodiments the transformer can be arranged in astep-dawn configuration. Other embodiments have other ratios ofwindings. The output can also be generated in the second stage withoutusing a transformer in yet other embodiments.

In this example, the transformer 70 is a center tap transformer. Theoscillating signal generated by the first stage 58 is provided to theprimary winding and the center tap, and operates in conjunction with apair of diodes to rectify the output signal. The output signal isgenerated at the secondary windings and supplied to the output terminal16. The ratio of the primary windings to the secondary windingsdetermines the amplification provided by the transformer 70.

In some embodiments the circuitry 20 further includes electroniccomponents, and/or programming, that are configured to automaticallyvary the output signal, which may include varying one or more of theoutput voltage, the output current, shape of the output voltagewaveform, and/or frequency of the output signal over time, withouthaving to adjust the variable controls (e.g., potentiometers 22, 24). Inone embodiment, the output signal may be changed over time by executingspecific computer code or a software program in the microprocessor. Inanother embodiment, the output signal may be randomly changedinexpensively by the inclusion of a typical flashing light emittingdiode (LED) 63 within the circuitry of the signal generator 10. FlashingLEDs automatically blink when supplied with electrical power,alternating between an “on” and “off” state, with the frequency offlashing between the two states depending on the input voltage. In oneembodiment, the flashing LED is placed in the electronic circuitrydownstream of the microprocessor and upstream of the amplifying circuitthat is connected to the output leads that are attached to the patientby the electrodes. The flashing LED, oscillating between an “on” and“off” state, is constantly switching the output current on and off,causing the signal generator 10 to vary the electrical output signal andvoltage over time, according to the flashing frequency of the flashingLED. In this manner, the LED acts as a repetitive timer for the outputsignal from the signal generator. And because the frequency of the LEDis dependent on its input voltage, adjusting the voltage from thepotentiometer will change the frequency of the flashing LED, so as toprovide an infinitely variable output signal to the patient.

Furthermore, the lower the quality of the components used to make theflashing LED, as with inexpensive flashing LEDs, the more variation orrandomness there will be in the consistency or stableness of thefrequency of the flashing for a given voltage. Accordingly, lowerquality flashing LEDs provide a flashing pattern that is more randomthan that of higher quality flashing LEDs. Therefore, in one embodiment,to achieve more randomness in the frequency of the electrical signalsent to the patient from the signal generator 10, it may be beneficialto use lower quality flashing LED within the circuitry as disclosedherein.

In still alternate embodiments, additional methods to vary the outputsignal and voltage over time are contemplated herein, without departingfrom the scope of the present disclosure. By varying the output signalin the manner disclosed herein, the patient's body is constantlyreacting to the changing output signal, rather than possibly becomingaccustomed to a constant output signal to which the venous system mightotherwise no longer respond after a short exposure thereto.

The signal generator 10 may also include at least one indicator 32, suchas an LED or other lighted indicator, to indicate to the medicalpractitioner utilizing the electrical stimulation apparatus 1 as to whenthe power to the apparatus is turned “on.” An additional indicator maybe included to indicate when the electrical signal is being sent to apatient. In one embodiment, the indicator may perform both functions,however, in alternate embodiments, separate indicators may be utilizedto communicate each of the two functions.

The apparatus 1 may also include programming and/or a display screenconfigured to communicate and display for the medical practitioner thereal time output voltage and signal, an initial set output voltage andsignal, fault conditions, stimulation apparatus fault diagnosticinformation, or any other such setting, output, or feedback informationas may be desired. In another embodiment, the apparatus 1 may include adisplay configured to graphically display the real time electricalinformation (e.g. the electrical signal and/or voltage vs. time) beingsent to the patient. In still further embodiments, the stimulationapparatus 1 may include data output programming and associated outputconnectors that are configured to permit the apparatus to be connectedto a separate, stand-alone external display for displaying any/all ofthe information disclosed herein.

In some embodiments the electronic circuitry 20 is arranged on one ormore circuit boards. The circuit boards include at least one substratelayer, and typically have at least one layer of electrical traces formedthereon to make electrical connections between the electroniccomponents. In some embodiments the electronic signal generator 10 isformed on the circuit board.

The output signal is sent from the signal generator 10 to the patient'sbody by two electrical leads 26 that are connected at a proximal end tothe signal generator 10, and at a distal end to a pair of electrodes 18.In one embodiment of the present disclosure, the electrodes 18 may beconfigured as a pair of cups or other containers 28, such as forexample, a pair of manicure nail soaking bowls or other such similarcontainers, that are configured to hold a liquid electrolyte solution 30into which at least some of the finger and thumb tips (or more) of apatient are to be submerged. In some embodiments the electrodes areconnected to or otherwise associated with the containers 28, such asbeing fastened to an interior of the container by an adhesive or moldedinto the container. The electrodes can also be placed into the containerwithout being securely fastened to the container in some embodiments. Insome embodiments the container is conductive, such that the containerfunctions as an electrode. In some embodiments the containers includeone or more recessed regions sized and shaped to receive at least thetips of the fingers of a hand, or the toes of a foot, therein. Thepurpose of suing an electrolyte solution is to provide a conductiveliquid medium into which the patient may place his fingers and throughwhich the electrical signal may be delivered to the patient. In oneembodiment, the electrolyte solution may be a mix of minerals and water.However, in alternate embodiments, the electrolyte solution may be anyother type of solution used for increasing electrical conductivitybetween the electrical leads and the skin of a patient.

While a previous embodiment disclosed the electrodes configured as smallcontainers for permitting the fingertips to be placed into anelectrolyte solution, the electrodes should not be limited to suchembodiment and in alternate embodiments may have alternateconfigurations as desired. For example, in alternate embodiments, theelectrodes may be alternate sized containers that permit the submersionof a patient's full hands, feet, or any portion of the patient's body,including but not limited to arms and/or legs, into an electrolytesolution in electrical communication with the signal generator. In stillalternate embodiments, the electrodes may be configured as a pair ofconductive electrode pads having a conductive gel or adhesive layerdisposed on one side thereof to help adhere the electrode pad to theskin of a patient and to aid in making good electrical contact betweenthe conductive pad and the patient's skin. Such electrode pads may besimilar to those used with transcutaneous electrical nerve stimulation(TENS) devices or portable defibrillators. Furthermore, in stillalternate embodiments, the electrodes may be one or more of a metalpin-type probe or metal plate that are contact based electrodes. Instill alternate embodiments, the electrode may be a finger clamp-typeprobe that is similar in mechanical structure to those used to measurepulse oximetry. In yet additional embodiments, the electrodes may beconductive garments, or other such contact-based electrode having analternate physical configuration, without departing from the scope ofthe disclosure herein. In yet an additional embodiment, the electrodesmay be configured as one or more electromagnets that generate a magneticfield, into which magnetic field the patient may place his hands, feet,or limbs. The electromagnetic field is configured to generate acomplementary electric signal in the patient's body via changes to themagnetic field. In such an embodiment, the patient is not directlyconnected to the signal generator.

In one embodiment, the electrical signal output from the signalgenerator 10 sent to a patient's limbs through the electrodes includesan electrical signal that is an alternating signal (AC). In oneembodiment, the AC signal sent to the patient has a frequency of 7.83 Hz(or 7.83 full alternating cycles per second). This means that the outputcircuit is interrupted 7.83 times per second. This frequency of 7.83 Hzhas been selected in one embodiment to provide the nerves of the patienttime to repolarize between successive output signals, and thus have timeto get prepared for the next subsequent output signal. By providingadequate time to allow the nerves to repolarize, the signal generated bythe signal generator 10 has a consistent effect on the skin, nerves, andmuscles in the vicinity of the electrodes.

However, while the above embodiment operates at a frequency of 7.83 Hz,the frequency of the output signal should not be read to be limited onlyto such specified frequency, and in alternate embodiments, the AC or DCsignal may have a different frequency without departing from the scopeof the present disclosure. In alternate embodiments, the frequency ofthe output signal may be any alternate frequency, depending on thespecific circuitry design of the signal generator. For example, in analternate embodiment, a different duty cycle or output cycle, or even adifferent waveform that is subsequently developed, may use a differentfrequency. Furthermore, in alternate embodiments, the signal generator10 may be configured to adjust the frequency or waveform of the outputsignal based on sensed feedback related to the physiological differencesbetween patients of different ages, the patient's circulatory systempatency, and other biomedical and/or bioelectrical aspects of thepatient's body. In one embodiment, the microprocessor in the signalgenerator 10 may further contain programming that adjusts the outputsignal for the changes that are usually associated with an agingpatient, such as thinner skin, more sensitive skin, skin that issensitive to bleeding, etc.

In one embodiment, the output voltage from the signal generator 10,which is set by at least one of the potentiometers 22, 24, is initiallyset to be within the range of between 0 volts and 90 volts. In anotherembodiment, each of the two output voltage channels may be set to bewithin the range of between 0 volts and 90 volts. However, in alternateembodiments, the potentiometers 22, 24 may have larger or smaller outputvoltage ranges than that disclosed herein, and may each be selectablyset to an initial output voltage value, or adjusted to a new outputvoltage value, within such larger or smaller voltage ranges, withoutdeparting from the scope of the present disclosure.

Feedback System.

The signal generator 10 may further include an integrated feedbacksystem that is configured to measure the resistance and capacitance ofthe patient's body during the time between each successive cycle of theoutput signal. In one embodiment, the feedback system utilizes a ten toone (10:1) audio transformer that responds to the electrical andcapacitive resistance (i.e., electrical back pressure) of the patient'sbody, as well as any changes thereto, in order to adjust the outputsignal sent to the patient. Each human body presents with an electricalresistance. This resistance can change with the body's weight,hydration, etc. This electrical resistance can also change during thetreatment. The signal generator 10 uses the audio transformer to measurethe electrical resistance of the patient's body and, in response,appropriately alter the output voltage and/or current transmitted to thepatient as part of the signal. In doing so, the signal may be alteredbased on the feedback from the feedback system to ensure that the signalgenerator 10 is eliciting the same clinical or physiological response inthe patient's body, even when the patient's bodily response to treatmentis changing (i.e. changes to the patient's electrical back pressure, orbodily resistance and/or capacitance).

A simple transformer performs the job of monitoring the electrical backpressure of the patient's body simply and inexpensively. When themicroprocessor, via the transformer electrical communication with thepatient, detects a very high electrical resistance in the patient'sbody, then very little current will flow from the signal generator intothe patient for a given constant output voltage from the signalgenerator to the patient. If the input current from the signal generatoris very low (as when powered by a small battery), and if the outputvoltage leads do not have much resistance, then the battery powerdecreases and the current drops significantly. The measured electricalresistance of the human body is fairly constant, but the capacitance ofthe human body can vary greatly. This is a concern, because the suddenrelease or electrical energy or charge from the capacitor-like parts ofthe human body can result in the body receiving a painful jolt ofelectricity that may potentially cause damage to the patient's nervousor cardiac system, and otherwise interrupt the desired clinical responsein the patient's body caused by the treatment.

The transformer of the feedback system filters an output voltage of thesignal generator, which voltage fluctuates over time according to apreprogrammed voltage waveform, to allow the specific portions of thevoltage waveform that are the most effective at eliciting the desiredvein distension response to pass through to the patient. The electricalback pressure in the patient causes a reaction in the patient's bodythat creates a resulting electrical signal from the patient's body thatcan be captured and read by the signal generator, which can then be usedas an input to adjust the output voltage of the next cycle of the outputsignal from the signal generator.

In alternate embodiments, the feedback mechanism may be specificprogramming within the microprocessor of the signal generator that isconfigured to monitor the feedback of the patient's electricalresistance and capacitance and, in turn, adjust the output signal sentto the patient based on the monitored feedback. In still alternateembodiments, the feedback system may utilize a plurality of sensorsconfigured to measure the patient's resistance and capacitance, or anyother such electrical component or computer code configured to measurefeedback resistance and capacitance, without departing from the scope ofthe present disclosure.

In one embodiment, the apparatus 1 can be configured to stop all outputsignals from the signal generator 10 and wait for the patient's body toreact to the last output signal. When the patient's body reacts to thelast signal, the patient's body produces a resulting electrical signalthat can be captured by the signal generator 10, analyzed, and used toalter the next output signal from the signal generator 10 that is sentto the patient. This can be done in real time with the appropriatemicroprocessor and software. In an alternate embodiment, if the feedbackmechanism of the signal generator measures a change in a patient'sbioelectrical resistance or capacitance of more than 10% betweensuccessive cycles of the output signals, the signal generator isconfigured to shut off or go into a fault mode, as a change of largerthan 10% may indicate that the patient's body is experiencing a stressresponse and no is longer responding to the output signals. In oneembodiment, the signal generator would automatically adjust the outputsignal waveform, voltage, and current based on the individual patient'sspecific physiology and related bioelectrical properties.

In still further embodiments, the signal generator includes software tocollect physiological data from the patient using the stimulationapparatus, including the patient's physiological response data. Thatdata can then be stored and analyzed by the signal generator and used tochange the output signal in real time, so as to optimize the outputsignal and the achieved venous response for the specific patient.

Included in the signal generator may be a microprocessor havingprogramming therein configured to control the amount of current andvoltage being sent to the patient via the electrodes, as well as theshape of the output voltage waveform that is being sent to the patient,monitor the electrical feedback received from the patient (i.e. thepatient's internal bodily resistance and capacitance), and automaticallyadjust, in real time, any of the voltage output, the current output, orthe shape of the voltage waveform being sent to the patient. Themicroprocessor may be any programmable microprocessor having any speedor internal memory size without departing form the scope of the presentdisclosure. In one embodiment, the microprocessor may include acomparator circuit configured to compare the original output signal sentto the patient from the signal generator to the returned signal from thepatient. The results of the comparison are then used by themicroprocessor to change the output signal proportionately to balancethe next output signal sent to the patient. In such an embodiment, themicroprocessor may have a baseline waveform stored in its memory whichis sent to the patient with the first signal. A response/reflect signalis then sent back to the microprocessor from the patient through thefeedback system, which response/reflex signal is also stored in themicroprocessor. Thereafter, the microprocessor adapts the next outgoingsignal based on the prior stored incoming response/reflex signal togently coax the patient's nerves to carry the best waveform, voltage,and current necessary to produce the greatest visible presentation ofthe vein. This comparative process ensures that the output signal beingset to the patient each time will continue to elicit the desiredphysiological and clinical response in the peripheral veins of thepatient, preventing the patient's body from getting accustomed to thesignal being sent.

Furthermore, the processor includes programming configured to maintain apredefined signal frequency. For example in one embodiment, themicroprocessor is programmed to maintain a preprogrammed signalfrequency of 7.83 Hz. However, in alternate embodiments, alternatefrequencies may be chosen without departing from the present disclosure.For example, in some patient groups or subsets, such as obese patients,geriatric patients, or neonatal patients, alternate signal frequenciesmay be needed to aid in eliciting the optimal venous presentationresults. In addition, in an embodiment, the microprocessor may beprogrammed and configured to continue to operate properly on aconstantly declining voltage, such as for example when the power supplyis a battery that slowly runs out of power over time and continued use.

Waveform Graph

FIG. 7 shows an exemplary graph of an embodiments of active portions ofa single cycle of a signal. The graph shows an output voltage (theY-axis) of the output signal, versus time in milliseconds (the X-Axis),that is able to illicit the desired vein distension and pain suppressionresponse in a patient. The shape of the signal, including the locationand amplitude of the various peaks and valleys therein, is an exemplarywaveform that is able to elicit active, signal-based enlargement of thetarget peripheral veins, which aids in the performing of venipuncture bymedical practitioners, for example.

Referring further to FIG. 7, a plurality of points 1-9 are identified onthe graphed waveform showing the output signal's output voltage vs.time. Point 1 on the graph corresponds to the beginning of a new cycleof the repetitive output signal, and indicates the initial outputvoltage from the signal generator that is selected to alert or stimulatea patient's sensory nerve (via its dendrites in the surface of the skin)to a change in condition. This initial output voltage initiates a tinyelectrical signal in the patient's body, having a unique voltage,current, and waveform, to be sent to the central nervous system so thebrain can monitor the extremities. In response, the brain sends ahealing signal back to that specific sensory dendrite from which thesignal to the brain originated.

Point 2 on the graph corresponds to the primary effective portion of thenerve stimulation signal. This point is the main output voltage in thenerve stimulating portion of the output signal that causes theperipheral nerves in the patient's limbs to over-react and causes asimultaneous tetany or contraction of the nearby muscles surrounding thetarget peripheral veins. This is the portion of the waveform that isadjusted via the knob of one of the potentiometers 22, 24 on the signalgenerator. In overweight patients, the voltage level at Point 2 isautomatically suppressed by a layer of fat in the skin. Accordingly, foroverweight patients, in order to get the signal to reach the nerves ofthe patient and overcome the resistance of the fat layer, it may benecessary to send a higher output voltage to the patient. This can beaccomplished by using a ten to one (10:1) audio transformer, or othersuch transformer, in the signal generator to amplify the output voltagesignal sent to the patient. Alternatively, the increasing of the voltageto overcome the resistance of the fat layer so the signal may reach thenerves may also be accomplished by the implementation of programmingcontained in the microprocessor.

Point 3 in the voltage waveform graph corresponds to the output voltagethat triggers the sensory nerve in the patient to “turn of” In thisregard, Point 3 is the voltage that triggers the nerve to be at rest andreset to its standby voltage, waiting to be used or triggered “on” againin the next subsequent cycle of the output signal. Point 4 in thevoltage waveform graph is the output voltage that cancels the positiveportion of the signal and balances the stimulation apparatus' nervesignal to allow the nerve time to reset itself, or repolarize.

Point 5 in the waveform graph corresponds to the muscle stimulationportion of the output signal, and is the output voltage that causes themuscles to stimulate the venous muscle pump that in turn causes theveins to distend and fill with blood. In the waveform presented in FIG.7, the length of time during which this portion of the signal is activeis small, however in some patients the length of time over which thisportion of the output voltage in the output signal is active will beadjusted to achieve the proper amount of motor muscle stimulation toactivate the venous muscle pump. The longer that this portion of thesignal is active, the more that the muscles are stimulated. In addition,the small muscles surrounding the veins require a different amount ofactive stimulation time to activate the venous muscle pump action thanthat of the larger muscles. This portion of the waveform also may beadjusted from patient to patient to achieve the optimal venous musclepump action in each patient.

Point 6 in the waveform graph is the point at which the motor musclestimulation is shut off to allow them to reset and get ready for thenext cycle of the signal. Point 7 in the waveform graph corresponds to areflex signal back pressure from the patient's peripheral nervoussystem, indicating that the nervous system is trying to take overcontrol of the nerves and muscles and stabilize the patient's muscle andnerve activity. Point 8 in the waveform graph corresponds to a period ofzero output voltage to the patient, and is part of the integratedfeedback loop that the peripheral nervous system uses to gently restorethe patient's baseline electrical potential back to its original restingelectrical potential, or internal voltage. In comfortable, relaxedpatients, their resting potential, or measured voltage, may be on theorder of 20 millivolts. However, in some patients who are anxious, theirmeasured resting potential may be zero volts, or a positive measuredvoltage, which are otherwise higher electrical potentials or voltagesthan a typical relaxed patient. This initial resting potentialmeasurement is used to setup the basic parameters of the first and eachsucceeding treatment output signal from the signal generator.

Point 9 in the waveform graph corresponds to the patient's baselinecondition, whereby there is no active output signal or voltage beingsent to the patient's body, and the patient is otherwise unaffected byany output signal from the stimulation apparatus. This also correspondsto the period during which the signal generator is monitoring thepatient's internal electrical potential and preparing to initiate a newcycle of the signal, and adjusting the active portion of the outputsignal based on the feedback monitored from the patient.

FIGS. 8-9 illustrate other example waveforms that can be used in otherembodiments, or with different subjects due to different characteristicsof the subjects.

In some embodiments, the waveform has one or more of the followingproperties. The highest voltage reached stimulates the musclessurrounding the veins. The width of the signal from the baseline untilthe return the baseline stimulates the nearby voluntary motor muscles tofunction as a venous muscle pump to empty the adjacent veins of blood.The return to baseline stops the action of both muscles. The negativepulse following the first return to baseline begins the return to theoriginal resting state of the muscles and nerves. The negative pulsedelivers a negative polarity pulse that with a volume of energy (e.g.,watts) that equals the energy delivered in the original positivepolarity phase. The second return to baseline finishes the polaritybalancing. The time period until the next signal allows the nerve andmuscle cells to re-organize and prepare for the next sequence ofstimulation. Other waveforms have other properties.

Apparatus Operation and Stimulation Action

In operation, the stimulation apparatus functions as follows. Theelectrodes are placed in electrical contact with the fingers or hands ofa patient. In one embodiment, this involves the patient placing thefingertips of each hand into separate containers of an electrolytesolution. The electrolyte solution in each container is placed inelectrical communication with the signal generator by separateelectrical leads that are terminated at one end in the electrolytesolution, and at the opposite end to output contacts of the signalgenerator. In alternate embodiments, the electrodes may be adhesivebacked pads that are affixed directly to the patient's skin.

The power source supplies power to the signal generator. The medicalpractitioner adjusts the output voltage to the patient by rotating anadjustment knob of at least one of two potentiometers. The signalgenerator is switched “on” and the preprogrammed electrical outputsignal is transmitted through the leads and electrodes to thefingertips, hands, and arms of the patient. The preprogrammed outputsignal includes a repetitive cycle of preprogrammed fluctuating outputvoltages at various specified points in time for each cycle. In oneembodiment, the initial output voltage may be set between 0 and 90 voltsand the signal delivered is less than one milliamp. However, inalternate embodiments, the output voltage range may be larger orsmaller, or cover a different voltage range than that disclosed in thepresent embodiment, and the output signal may be larger than 1 milliampwithout departing from the scope of the present disclosure.

Each cycle of the output electrical signal includes a period of activeoutput voltage and a period of rest, where no output voltage is beingimparted to the patient's limbs. The preprogrammed output voltageincludes several phases including: an initiation phase that alerts thepatient's sensory nerve to the presence of the output voltage; a primarynerve stimulation phase that causes the peripheral nerves to force themotor muscles surrounding the peripheral target veins to contract; anend to the nerve stimulation phase that turns “off” the sensory nerve; abalancing phase that cancels the stimulation signals that were sent tothe nerves to allow the nerves to reset; a muscle stimulation phase thatactivates the venous muscle pump; a shutdown phase that ends theactivation of the muscles; an electrical back pressure phase; anelectrical feedback phase; and a rest phase with no active voltageoutput to allow the patient's system time to reset before the next cyclebegins. This cycling part of the waveform used in some embodiments isnot required in all embodiments. Other embodiments utilize otherwaveforms that cause one or more of the actions described herein.Additionally, suitable waveforms may vary relative to the patient'sphysiology, the design and limitations of the electronic circuitry,and/or the method used to deliver the signals to the patient.

The result of the repetitive electrical cycles in the output signal thatare imparted to the patient is a physiological response in the patientas follows. One portion of the generated electrical signal stimulatesthe muscles near the electrodes to contract and relax. These muscles arecircular in nature and when they contract they form a tube. This tube islarger than normal and creates a vacuum which can have the effect ofdrawing in whatever blood is available via the capillaries and thenearby arteries. In addition, part of the waveform stimulates theadjacent muscles which act as a venous muscle pump to increase the localblood pressure in the veins, thus adding more blood to the now visuallyobvious and distended veins. This venous muscle pump is the body's wayof moving blood from the arteries and capillaries back to the heart. Themultitude of valves present in the veins prevent retrograde blood flow,thus aiding the enlarging of the target veins internal volume for easieraccess for venipuncture. For some patient groups, such as geriatricpatients, this venous muscle pump action may be further aided inconjunction with the presently disclosed electrical venous stimulationapparatus, by the use of a tourniquet applied between the target veinand the heart.

The electrical venous stimulation apparatus of some embodiments worksbest to present the veins in the back of the hands, top of the feet, andthe forearms.

In embodiment, the electrical venous stimulation apparatus furtheroperates as a TENS device in that there is a portion of the outputvoltage waveform that is configured to numb the tissue adjacent theelectrodes (and accordingly the target vein site). This includedfunctionality makes the process of inserting a needle into a target veinwhile using the electrical venous stimulation apparatus less painful tothe patient when the needle stick actually occurs. In embodiments havingtwo potentiometers, the second potentiometer controls the output voltagechannel that creates the TENS device functionality. The second outputchannel can be configured to attach directly on the skin of the patientnearby the projected needle stick site to focus the numbing effect to aspecifically local area. The second channel can be configured to performthis nerve deadening functions specifically. Thus in one embodiment, oneoutput voltage channel is used to achieve the displaying of an enlarged,engorged vein, and the other output voltage channel is used to numb thearea of the needle stick.

The apparatus of the present disclosure is configured to non-invasivelyalter the physiology of the peripheral veins that are targeted forvenipuncture in the limbs of a patient using an active electricalsignal, rather than using passive means traditionally used, or requiringthe use of a tourniquet. In an aspect of the present disclosure, anactive signal imparted to the skin of a patient by the apparatus elicitsa physiological response and a change in condition/behavior of thetarget vein, causing the vein to fill with blood and becomedistended/enlarged and become more rigid and therefore easier tovisualize under the skin, as shown in FIG. 5 during and after theelectrical stimulation (compare with FIG. 4, which illustrates the handsbefore the electrical stimulation). In this manner, using such anapparatus and methodology as disclosed herein, it becomes easier formedical practitioners to locate the target vein and achieve successfuland proper venipuncture. No other active device currently exists thatnon-invasively changes the physiology of the tissue in and around thetarget veins to aid in locating the target vein and increasing the easeof achieving successful and proper venipuncture without the need formultiple attempts.

As discussed herein, one embodiment is a method of accessing a vein of aperson, the method comprising: receiving a portion of a limb of theperson into a container; supplying a liquid electrolytic solution intothe container, wherein the liquid electrolytic solution is in contactwith the portion of the limb; electrically stimulating the portion ofthe limb with at least one signal generated by an electrical signalgenerator, the electrical signal provided to the electrolytic solutionby at least one electrode in contact with the liquid electrolyticsolution; causing at least one vein in the limb of the person to distendin response to the electrical stimulation; and inserting a tip of aneedle into the vein while it is distended to access the vein.

The various embodiments described above are provided by way ofillustration only and should not be construed to limit the claimsattached hereto. Those skilled in the art will readily recognize variousmodifications and changes that may be made without following the exampleembodiments and applications illustrated and described herein, andwithout departing from the true spirit and scope of the followingclaims.

What is claimed is:
 1. An electrical venous stimulation apparatus forcausing a target vein in a subject to enlarge and fill with blood undera surface of the subject's skin to enhance identification of suitableveins for cannulation, the electrical venous stimulation apparatuscomprising: a power supply; a signal generator powered by the powersupply, the signal generator configured to generate an electrical outputsignal; multiple electrodes in electrical communication with the signalgenerator and configured to be placed in electrical communication withthe subject at different locations; and wherein the electrical outputsignal includes an output voltage, electrical current, and a waveformthat changes with time in a preprogrammed repeating cycle, the outputvoltage, electrical current, and waveform being configured to elicit aphysiological response that non-invasively alters a physiology of atarget vein, wherein the target vein is caused to enlarge and fill withblood under the surface of the subject's skin, wherein the waveformcomprises: a first phase in which a positive polarity pulse above abaseline voltage is delivered; a second phase in which a negativepolarity pulse below a baseline voltage is delivered; and a third phasein which no voltage is delivered for a time period prior to a nextsequence of stimulation.
 2. The electrical venous stimulation apparatusof claim 1, further comprising a first of the electrodes beingconfigured to provide the electrical output signal to a limb of thesubject, and a second of the electrodes being configured to provide theelectrical output signal to the limb of the subject or a second limb ofthe subject.
 3. The electrical venous stimulation apparatus of claim 1,wherein the output voltage, electrical current, and waveform are furtherconfigured to suppress pain signals at a venous needle stick site of thesubject.
 4. The electrical venous stimulation apparatus of claim 1,wherein the second phase comprises: a first stage in which a firstportion of the negative polarity pulse is delivered; a first return tothe baseline voltage; a second stage in which a second portion of thenegative polarity pulse is delivered; and a second return to thebaseline voltage.
 5. The electrical venous stimulation apparatus ofclaim 1, wherein energy delivered in the first phase is balanced byenergy delivered in the second phase.
 6. The electrical venousstimulation apparatus of claim 1, wherein the signal generator isprogrammed to: measure, during the third phase, a resting potential ofthe subject; and prepare the next sequence of stimulation based on theresting potential.
 7. The electrical venous stimulation apparatus ofclaim 1, wherein the signal generator is programmed to: monitorbiological electrical feedback based on electrical resistance andcapacitance of the subject; compare the biological electrical feedbackfrom the subject with a transmitted output signal; and automaticallyadjust subsequent output signals to be sent to the subject based on thecomparison between the transmitted output signal and the biologicalelectrical feedback.
 8. The electrical venous stimulation apparatus ofclaim 1, wherein a highest voltage reached stimulates musclessurrounding the target vein.
 9. The electrical venous stimulationapparatus of claim 1, wherein the negative polarity pulse causes areturn to a resting state of muscles.
 10. The electrical venousstimulation apparatus of claim 1, wherein the negative polarity pulse isdelivered with a power that equals the power delivered with the positivepolarity pulse.
 11. The electrical venous stimulation apparatus of claim1, wherein the electrical output signal is an AC signal with a currentof less than one milliamp and a frequency of between 4 and 12 Hz, andthe output voltage is between 0 and 90 volts.
 12. The electrical venousstimulation apparatus of claim 1, wherein the target vein is caused todistend under the surface of the subject's skin.
 13. The electricalvenous stimulation apparatus of claim 1, further comprising electricalleads configured to provide the electrical output signal generated bythe signal generator to the electrodes, each of electrical leadsconnecting a respective one of the electrodes to the signal generator.14. The electrical venous stimulation apparatus of claim 1, furthercomprising a variable control configured to adjust a magnitude of theoutput voltage.
 15. The electrical venous stimulation apparatus of claim1, wherein a magnitude of the output voltage is variable from about 0 toabout 40 volts.
 16. The electrical venous stimulation apparatus of claim1, wherein the signal generator further comprises: a power switch; anoscillator including an integrated circuit; a variable controlconfigured to adjust a magnitude of the output voltage in response to aninput; and output circuitry comprising: a first stage includingoperational amplifiers and a capacitor; and a second stage including acenter tap transformer.
 17. The electrical venous stimulation apparatusof claim 1, wherein each of the electrodes comprises an electrode padhaving an adhesive layer disposed on one side thereof.
 18. Theelectrical venous stimulation apparatus of claim 1, wherein thedifferent locations include locations on a limb of the subject.
 19. Theelectrical venous stimulation apparatus of claim 1, wherein one of thedifferent locations is the palm of the subject.
 20. The electricalvenous stimulation apparatus of claim 1, wherein one of the differentlocations is the bicep of the subject.
 21. A method of stimulating avein in a subject by causing a target vein in a subject to enlarge andfill with blood under a surface of the subject's skin to enhanceidentification of suitable veins for cannulation, the method comprising:placing multiple electrodes in electrical communication with the subjectat different locations; and generating an electrical output signalincluding an output voltage, electrical current, and a waveform thatchanges with time in a preprogrammed repeating cycle, the outputvoltage, electrical current, and waveform being configured to elicit aphysiological response that non-invasively alters a physiology of atarget vein, wherein the target vein is caused to enlarge and fill withblood under the surface of the subject's skin, wherein the waveformcomprises: a first phase in which a positive polarity pulse above abaseline voltage is delivered; a second phase in which a negativepolarity pulse below a baseline voltage is delivered; and a third phasein which no voltage is delivered for a time period prior to a nextsequence of stimulation; and transmitting the electrical output signalto the subject via the multiple electrodes.
 22. The method of claim 21,wherein placing the multiple comprises placing a first of the electrodesat a limb of the subject and a second of the electrodes at the limb ofthe subject or a second limb of the subject.
 23. The method of claim 21,wherein the transmitting comprises suppressing pain signals at a venousneedle stick site of the subject.
 24. The method of claim 21, whereinthe second phase comprises: a first stage in which a first portion ofthe negative polarity pulse is delivered; a first return to the baselinevoltage; a second stage in which a second portion of the negativepolarity pulse is delivered; and a second return to the baselinevoltage.
 25. The method of claim 21, wherein energy delivered in thefirst phase is balanced by energy delivered in the second phase.
 26. Themethod of claim 21, further comprising: measuring, during the thirdphase, a resting potential of the subject; and preparing the nextsequence of stimulation based on the resting potential.
 27. The methodof claim 21, further comprising: monitoring biological electricalfeedback based on electrical resistance and capacitance of the subject;comparing the biological electrical feedback from the subject with atransmitted output signal; and automatically adjusting subsequent outputsignals to be sent to the subject based on the comparison between thetransmitted output signal and the biological electrical feedback. 28.The method of claim 21, wherein a highest voltage reached stimulatesmuscles surrounding the target vein.
 29. The method of claim 21, whereinthe negative polarity pulse causes a return to a resting state ofmuscles.
 30. The method of claim 21, wherein the negative polarity pulseis delivered with a power that equals the power delivered with thepositive polarity pulse.
 31. The method of claim 21, wherein theelectrical output signal is an AC signal with a current of less than onemilliamp and a frequency of between 4 and 12 Hz, and the output voltageis between 0 and 90 volts.
 32. The method of claim 21, wherein thetransmitting comprises causing the target vein to distend under thesurface of the subject's skin.
 33. The method of claim 21, furthercomprising adjusting a magnitude of the output voltage according to aninput received at a variable control.
 34. The method of claim 21,wherein a magnitude of the output voltage is variable from about 0 toabout 40 volts.
 35. The method of claim 21, wherein a tourniquet isapplied subsequent to the stimulation.
 36. The method of claim 35,wherein peripheral intravenous cannulation is performed on the subjectsubsequent to the stimulation.